Composition for forming underlayer coating for lithography containing epoxy compound and carboxylic acid compound

ABSTRACT

There is provided an underlayer coating forming composition for lithography that is used in lithography process of manufacture of semiconductor device; and an underlayer coating having a high dry etching rate compared with photoresist. Concretely, it is a composition for forming an underlayer without use of crosslinking reaction by an strong acid catalyst, and an underlayer coating forming composition containing a component having an epoxy group (a polymer, a compound) and a component having a phenolic hydroxyl group, a carboxyl group, a protected carboxyl group or an acid anhydride structure (a polymer, a compound).

TECHNICAL FIELD

The present invention relates to a novel composition for formingunderlayer coating for lithography, an underlayer coating formed fromthe composition and a method for forming photoresist pattern by use ofthe underlayer coating. In addition, the present invention relates to anunderlayer coating for lithography that can be used for an underlayeranti-reflective coating for reducing reflection of exposure irradiationlight from a semiconductor substrate to a photoresist layer formed onthe substrate in a lithography process of the manufacture ofsemiconductor devices, a flattening coating for flattening asemiconductor substrate having unevenness, a coating for preventingcontamination of a photoresist layer due to substances generated from asemiconductor substrate on baking under heating, and the like; acomposition for forming the underlayer coating, and a method for formingthe underlayer coating. Further, the present invention relates to acomposition for forming underlayer coating for lithography that can beused for filling holes formed on a semiconductor substrate.

BACKGROUND ART

Conventionally, in the manufacture of semiconductor devices,micro-processing by lithography using a photoresist has been carriedout. The micro-processing is a processing method comprising forming athin film of a photoresist on a semiconductor substrate such as asilicon wafer, irradiating actinic rays such as ultraviolet rays througha mask pattern on which a pattern for a semiconductor device isdepicted, developing it to obtain a photoresist pattern, and etching thesubstrate using the photoresist pattern as a protective film, therebyforming fine unevenness corresponding to the pattern on the surface ofthe substrate. However, in recent progress in high integration ofsemiconductor devices, there has been a tendency that shorter wavelengthactinic rays are being used, i.e., ArF excimer laser beam (193 nm) hasbeen taking the place of KrF excimer laser beam (248 nm). Along withthis change, influences of random reflection and standing wave of asubstrate have become serious problems. Accordingly, it has been widelystudied to provide an anti-reflective coating between the photoresistand the substrate (Bottom Anti-Reflective Coating, BARC) in order toresolve the problem. As the anti-reflective coating, from a viewpoint ofeasy of use, many considerations have been done on organicanti-reflective coatings made of a light absorbing substance and apolymer compound and the like. For example, mention may be made of theacrylic resin type anti-reflective coating having a hydroxyl group beinga crosslinking reaction group and a light absorbing group in the samemolecule and the novolak resin type anti-reflective coating having ahydroxyl group being a crosslinking reaction group and a light absorbinggroup in the same molecule (see, for example U.S. Pat. Nos. 5,919,599and 5,693,691).

The physical properties desired for organic anti-reflective coatinginclude high absorbance to light and radioactive rays, no intermixingwith the photoresist layer (being insoluble in photoresist solvents), nodiffusion of low molecular substances from the anti-reflective coatinginto the topcoat photoresist upon baking under heating, and a higher dryetching rate than the photoresist (see, for example, Tom Lynch et al.,“Properties and Performance of Near UV Reflectivity Control Layers”, US,in Advances in Resist Technology and Processing XI, Omkaram Nalamasued., Proceedings of SPIE, 1994, Vol. 2195, p. 225-229; G. Taylor et al.,“Methacrylate Resist and Antireflective Coatings for 193 nmLithography”, US, in Microlithography 1999: in Advances in ResistTechnology and Processing XVI, Will Conley ed., Proceedings of SPIE,1999, Vol. 3678, p. 174-185; and Jim D. Meador et al., “Recent Progressin 193 nm Antireflective Coatings, US, in Microlithography 1999: inAdvances in Resist Technology and Processing XVI, Will Conley ed.,Proceedings of SPIE, 1999, Vol. 3678, p. 800-809).

In recent years, in order to solve interconnection delay that has becomeclear with miniaturization in pattern rule of semiconductor devices, ithas been considered to use copper as interconnect material, and to applyDual Damascene process as interconnect forming method on thesemiconductor device. And, in Dual Damascene process, via holes areformed and an anti-reflective coating is formed on a substrate having ahigh aspect ratio. Therefore, the anti-reflective coating for use inthis process is required to have filling property by which holes can befilled without gap, flattening property by which a flat coating can beformed on the surface of substrate, and the like.

However, it is difficult to apply organic material for anti-reflectivecoating on a substrate having a high aspect ratio, and in recent years,material with particular emphasis on filling property or flatteningproperty has been developed (see, for example JP 2000-294504 A, JP2002-47430 A, JP 2002-190519 A and WO 02/05035 pamphlet,).

In addition, in the production of devices such as semiconductors, inorder to reduce poisoning effect of a photoresist layer induced by adielectric layer, there is disclosed a method in which a barrier layerformed from a composition containing a crosslinkable polymer and thelike is provided between the dielectric layer and the photoresist layer(see, for example JP 2002-128847 A).

As mentioned above, in the recent manufacture of semiconductor devices,in order to attain several effects represented by anti-reflectiveeffect, it comes to provide an organic underlayer coating formed from acomposition containing an organic compound between a semiconductorsubstrate and a photoresist layer, that is, as an underlayer of thephotoresist.

As the underlayer coating is required to cause no intermixing, acrosslinking reaction is utilized for the formation of the underlayercoating in many cases. And, as the composition for forming such acrosslinkable underlayer coating, a composition comprising a polymer, acrosslinking agent and a sulfonic acid compound as a crosslinkingcatalyst is used (see, for example U.S. Pat. No. 5,919,599, JP2000-294504, JP Patent 200247430 and WO 02/05035 pamphlet). However, asthe compositions contain a strong acid being the sulfonic acid compound,they are anticipated to have a problem in shelf stability.

Therefore, an underlayer coating formed by use of crosslinking reactionfor which no strong acid catalyst is required, and a compositiontherefor are desired.

In the meanwhile, it is known a technique in which tris(hydroxyalkyl)isocyanurate substituted with an aromatic compound or a an alicycliccompound is used as a broad ultraviolet light absorber (see, for exampleJP 11-279523 A), and an anti-reflective coating forming compositioncontaining a cyanuric acid compound (see, for example WO 02/86624pamphlet).

Taking the above-mentioned present status into account, the presentinventors have eagerly studied, and as a result of it, found that theuse of a compound having an epoxy group (a polymer compound) and acompound having a phenolic hydroxy group, a carboxyl group, a protectedcarboxyl group or an acid anhydride structure (a polymer compound) makespossible to form an underlayer coating by use of crosslinking reactionfor which a strong acid catalyst such as a sulfonic acid compound andthe like is not required, and they completed the present invention.

That is, an object of the present invention is to provide a compositionfor forming underlayer coating that can be used for the production ofsemiconductor devices, and to provide an underlayer coating forlithography that causes no intermixing with a photoresist applied andformed as an upper layer and that has a high dry etching rate comparedwith the photoresist, and an underlayer coating forming composition forforming the underlayer coating. Further, another object of the presentinvention is to provide an underlayer coating formed by use ofcrosslinking reaction for which no strong acid catalyst is required, amethod for forming the underlayer coating and an underlayer coatingforming composition therefor.

Further, an object of the present invention is to provide an underlayercoating for lithography that can be used for an underlayeranti-reflective coating for reducing reflection of exposure irradiationlight from a semiconductor substrate to a photoresist layer formed onthe substrate in a lithography process of the manufacture ofsemiconductor devices, a flattening coating for flattening asemiconductor substrate having unevenness, a coating for preventingcontamination of a photoresist layer due to substances generated from asemiconductor substrate on baking under heating; a composition forforming the underlayer coating. And another object of the presentinvention is to provide a method for forming underlayer coating forlithography by use of the underlayer coating forming composition, and amethod for forming a photoresist pattern.

DISCLOSURE OF INVENTION

The present invention relates to the following aspects:

as a first aspect, an underlayer coating forming compositioncharacterized by comprising a polymer compound having an epoxy group anda polymer compound having a phenolic hydroxyl group, a carboxyl group, aprotected carboxyl group or an acid anhydride structure;

as a second aspect, an underlayer coating forming compositioncharacterized by comprising a polymer compound having an epoxy group anda compound with a molecular weight of 2000 or less having at least twophenolic hydroxyl groups, carboxyl groups, protected carboxyl groups oracid anhydride structures;

as a third aspect, an underlayer coating forming compositioncharacterized by comprising a compound with a molecular weight of 2000or less having at least two epoxy groups and a polymer compound having aphenolic hydroxyl group, a carboxyl group, a protected carboxyl group oran acid anhydride structure;

as a fourth aspect, an underlayer coating forming compositioncharacterized by comprising a polymer compound having a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure and an epoxy group;

as a fifth aspect, the underlayer coating forming composition asdescribed in the first or third aspect, wherein the polymer compoundhaving a carboxyl group is a compound having acrylic acid or methacrylicacid as a unit structure;

as a sixth aspect, the underlayer coating forming composition asdescribed in the first or third aspect, wherein the polymer compoundhaving a phenolic hydroxyl group is a compound having hydroxystyrene asa unit structure;

as a seventh aspect, the underlayer coating forming composition asdescribed in the third aspect, wherein the compound with a molecularweight of 2000 or less having at least two epoxy groups is a compoundhaving at least three epoxy groups and no aromatic ring structure;

as an eighth aspect, the underlayer coating forming composition asdescribed in the second aspect, wherein the compound with a molecularweight of 2000 or less having at least two carboxyl groups is a compoundof formula (1)

wherein p and q is a number of 1 to 6, R₁ is hydrogen atom, C₁₋₆ alkylgroup, C₃₋₆ alkenyl group, benzyl group, phenyl group or —(CH₂)_(r)COOHwherein r is a number of 1 to 6;

as a ninth aspect, the underlayer coating forming composition asdescribed in the third aspect, wherein the compound with a molecularweight of 2000 or less having at least two epoxy groups is a compound offormula (2)

wherein A₁, A₂ and A₃ each are hydrogen atom, methyl group or ethylgroup, R₂ is hydrogen atom, C₁₋₆ alkyl group, C₃₋₄ alkenyl group, benzylgroup, phenyl group or a group of formula (3)

as a tenth aspect, the underlayer coating forming composition asdescribed in the second aspect, wherein the compound with a molecularweight of 2000 or less having at least two phenolic hydroxyl groups isat least one compound selected from the group consisting of ahydroxystyrene oligomer, a substituted bi-phenol compound, a substitutedtris-phenol compound, a methylolated phenol compound, a methylolatedbisphenol compound, a substituted phenol novolak and a substitutedcresol novolak;

as an eleventh aspect, the underlayer coating forming composition asdescribed in any one of the first to tenth aspects, further comprising alight absorbing compound;

as a twelfth aspect, a method for forming an underlayer coating for usein manufacture of semiconductor device, comprising coating theunderlayer coating forming composition as described in any one of thefirst to eleventh aspects on a substrate and baking it;

as a thirteenth aspect, a method for forming photoresist pattern for usein manufacture of semiconductor device, comprising coating theunderlayer forming composition as described in any one of the first toeleventh aspects on a semiconductor substrate, and baking it to form anunderlayer coating, forming a photoresist layer on the underlayercoating, exposing the semiconductor substrate covered with theunderlayer coating and the photoresist layer to light, and developingthe photoresist layer after the exposure to light; and

as a fourteenth aspect, the method for forming photoresist pattern asdescribed in the thirteenth aspect, wherein the exposure to light iscarried out with a light of a wavelength of 248 nm, 193 nm or 157 nm.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention relates to an underlayer coating formingcomposition comprising a polymer compound having an epoxy group and apolymer compound having a phenolic hydroxyl group, a carboxyl group, aprotected carboxyl group or an acid anhydride structure; an underlayercoating forming composition comprising a polymer compound having anepoxy group and a compound with a molecular weight of 2000 or lesshaving at least two phenolic hydroxyl groups, carboxyl groups, protectedcarboxyl groups or acid anhydride structures; an underlayer coatingforming composition comprising a compound with a molecular weight of2000 or less having at least two epoxy groups and a polymer compoundhaving a phenolic hydroxyl group, a carboxyl group, a protected carboxylgroup or an acid anhydride structure; and an underlayer coating formingcomposition comprising a polymer compound having an epoxy group and aphenolic hydroxyl group, a carboxyl group, a protected carboxyl group oracid anhydride structure.

The underlayer coating forming composition of the present inventionbasically comprises a polymer compound or a compound with a molecularweight of 2000 or less having an epoxy group, a polymer compound or acompound with a molecular weight of 2000 or less having a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure, or a polymer compound having a phenolic hydroxylgroup, a carboxyl group, a protected carboxyl group or an acid anhydridestructure, and a solvent, and as arbitrary components a light absorbingcompound, a surfactant or the like. The solid content in the underlayercoating forming composition of the present invention is for example 0.1to 70 mass %, or for example 0.1 to 50 mass %, or 0.5 to 50 mass %. Inthis specification, the solid content means all components in theunderlayer coating forming composition from which the solvent componentis excluded. The proportion of the component having an epoxy group (apolymer compound, a compound) and the component having a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure (a polymer compound, a compound) in the solidcontent is 70 mass % or more, for example 80 to 100 mass %, or 80 to 99mass %, or 90 to 99 mass %.

The underlayer coating forming composition according to the presentinvention contains a polymer compound having an epoxy group and apolymer compound having a phenolic hydroxyl group, a carboxyl group, aprotected carboxyl group or an acid anhydride structure.

As the polymer compound having an epoxy group, any polymer having anepoxy group can be used without any limitation. Such a polymer compoundcan be produced by addition polymerization by using a additionpolymerizable monomer having an epoxy group, or by reaction of a polymercompound having a hydroxyl group with a compound having an epoxy groupsuch as epichlorohydrin, glycidyl tosylate or the like.

The addition polymerizable monomer having an epoxy group includesglycidyl acrylate, glycidyl methacrylate or the like. And, the polymercompound having an epoxy group is produced from only one of the monomersor from a combination of two or more monomers.

In addition, the polymer compound having an epoxy group in the presentinvention may be a polymer compound produced by polymerization of theaddition polymerizable monomer having an epoxy group with other additionpolymerizable monomer.

The other addition polymerizable monomer includes an acrylate compound,a methacrylate compound, an acrylamide compound, a methacrylamidecompound, a vinyl compound, a styrene compound, a maleimide compound,maleic anhydride, acrylonitrile and the like.

The acrylate compound includes methyl acrylate, ethyl acrylate,isopropyl acrylate, benzyl acrylate, naphthyl acrylate, anthrylacrylate, anthrylmethyl acrylate, phenyl acrylate, 2-hydroxyethylacrylate, 2-hydroxypropyl acrylate, 2,2,2-trifluoroethyl acrylate,4-hydroxybutyl acrylate, isobutyl acrylate, tert-butyl acrylate,cyclohexyl acrylate, isobornyl acrylate, 2-methoxyethyl acrylate,methoxytriethylene glycol acrylate, 2-ethoxyethyl acrylate,tetrahydrofurfuryl acrylate, 3-methoxybutyl acrylate,2-methyl-2-adamantyl acrylate, 2-ethyl-2-adamantyl acrylate,2-propyl-2-adamanthyl acrylate, 2-methoxybutyl-2-adamantyl acrylate,8-methyl-8-tricyclodecyl acrylate, 8-ethyl-8-tricyclodecyl acrylate,5-acryloyloxy-6-hydroxynorbornene-2-carboxylic-6-lactone and the like.

The methacrylate compound includes ethyl methacrylate, n-propylmethacrylate, n-pentyl methacrylate, cyclohexyl methacrylate, benzylmethacrylate, naphthyl methacrylate, anthryl methacrylate, anthrylmethylmethacrylate, phenyl methacrylate, 2-phenylethyl methacrylate,2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,2,2,2-trifluoroethyl methacrylate, 2,2,2-trichloroethyl methacrylate,methyl acrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate,isodecyl methacrylate, n-lauryl methacrylate, n-stearyl methacrylate,methoxydiethylene glycol methacrylate, methoxy polyethylene glycolmethacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate,tert-butyl methacrylate, isostearyl methacrylate, n-butoxyethylmethacrylate, 3-chloro-2-hydroxypropyl methacrylate,2-methyl-2-adamantyl methacrylate, 2-ethyl-2-adamantyl methacrylate,2-propyl-2-adamanthyl methacrylate, 2-methoxybutyl-2-adamantylmethacrylate, 8-methyl-8-tricyclodecyl methacrylate,8-ethyl-8-tricyclodecyl methacrylate,5-methacryloyloxy-6-hydroxynorbornene-2-carboxylic-6-lactone and thelike.

In addition, the acrylate compound and methacrylate compound include thecompounds of formulae (a) to (g)

The acrylamide compound includes acrylamide, N-methyl acrylamide,N-ethyl acrylamide, N-benzyl acrylamide, N-phenyl acrylamide,N,N-dimethyl acrylamide and the like.

The methacrylamide compound includes methacrylamide, N-methylmethacrylamide, N-ethyl methacrylamide, N-benzyl methacrylamide,N-phenyl methacrylamide, N,N-dimethyl methacrylamide and the like.

The vinyl compound includes vinyl ether, methyl vinyl ether, benzylvinyl ether, 2-hydroxyethyl vinyl ether, phenyl vinyl ether, propylvinyl ether and the like.

The styrene compound includes styrene, methyl styrene, chloro styrene,bromo styrene and the like.

The maleimide compound includes maleimide, N-methyl maleimide, N-phenylmaleimide, N-cyclohexyl maleimide and the like.

The polymer compound having an epoxy group can be also produced byreaction of a polymer compound having a hydroxyl group with a compoundhaving an epoxy group such as epichlorohydrin, glycidyl tosylate or thelike. For example, epoxy phenol novolak produced from phenol novolak andepichlorohydrin and further epoxy cresol novolak, epoxy naphthol novolakand the like can be mentioned.

Specific examples of the polymer compound having an epoxy group used forthe underlayer coating forming composition according to the presentinvention include for example polyglycidyl acrylate, polyglycidylmethacrylate, a copolymer of glycidyl methacrylate and benzylmethacrylate, a copolymer of glycidyl acrylate and ethyl methacrylate, acopolymer of glycidyl methacrylate and 2-hydroxypropyl methacrylate, acopolymer of glycidyl methacrylate and benzyl methacrylate and2-hydroxyethyl methacrylate, a copolymer of glycidyl methacrylate andstyrene, a copolymer of glycidyl methacrylate and styrene and 2-hydroxyethyl acrylate and the like,

As the polymer compound having a phenolic hydroxyl group, a carboxylgroup, a protected carboxyl group or an acid anhydride structure, anypolymer compound having a phenolic hydroxyl group, a carboxyl group, aprotected carboxyl group or an acid anhydride structure may be usedwithout any limitation. In the present invention, the protected carboxylgroup includes a hemiacetal ester form obtained from carboxyl group withan alkyl vinyl ether, an amide form obtained from carboxyl group with anamine, an ester form obtained from carboxyl group with an alcohol, atert-butyl ester form obtained from carboxyl group with isobutene, or asilyl ester form obtained from carboxyl group with a silyl halidecompound, and the like. The protected carboxyl group includes forexample the groups of formulae (i) to (m)

wherein R₃ is C₁₋₆ alkyl group, benzyl group or phenyl group. R₃includes for example methyl group, ethyl group, isopropyl group andn-butyl group, etc.

Such a polymer compound can be produced by addition polymerization byusing an addition polymerizable monomer having a phenolic hydroxylgroup, a carboxyl group, a protected carboxyl group or an acid anhydridestructure.

The addition polymerizable monomer having a phenolic hydroxyl groupincludes hydroxy styrene and the like.

The addition polymerizable monomer having a carboxyl group includesacrylic acid, methacrylic acid, vinyl benzoate, vinyl acetate and thelike.

The addition polymerizable monomer having a protected carboxyl groupincludes methacrylic acid hemiacetal ester compounds such as1-methoxyethyl methacrylate, 1-ethoxyethyl methacrylate,1-isopropoxyethyl methacrylate, etc., acrylic acid hemiacetal estercompounds such as 1-methoxyethyl acrylate, 1-tert-butoxyethyl acrylate,1-isopropoxyethyl acrylate, etc., maleic acid hemiacetal estercompounds, fumaric acid hemiacetal ester compounds, itaconic acidhemiacetal ester compounds, acrylamide compounds, methacrylamidecompounds, acrylates, methacrylates, tert-butyl methacrylate, tert-butylacrylate, trimethyl silyl acrylate, trimethyl silyl methacrylate, andthe like.

The addition polymerizable monomer having an acid anhydride structureincludes maleic anhydride, or methacrylate, acrylate or vinyl compoundhaving non-cyclic anhydride, and the like.

In addition, the polymer compound having a phenolic hydroxyl group, acarboxyl group, a protected carboxyl group or an acid anhydridestructure can be produced from only one of the monomers or from acombination of two or more monomers.

Further, as the polymer compound having a phenolic hydroxyl group, acarboxyl group, a protected carboxyl group or an acid anhydridestructure, polymer compounds produced by polymerization of theabove-mentioned addition polymerizable monomer having a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure with other addition polymerizable monomer can beused.

The other addition polymerizable monomer includes the acrylate compound,methacrylate compound, acrylamide compound, methacrylamide compound,vinyl compound, styrene compound, maleimide compound, maleic anhydride,acrylonitrile and the like, as mentioned above.

Specific examples of the polymer compound having a phenolic hydroxylgroup, a carboxyl group, a protected carboxyl group or an acid anhydridestructure used for the underlayer coating forming composition accordingto the present invention include for example poly(acrylic acid),poly(methacrylic acid), a copolymer of acrylic acid and benzylmethacrylate, poly(4-hydroxystyrene), a copolymer of methacrylic acidand methyl methacrylate and 2-hydroxyethyl acrylate, a copolymer ofmethacrylic acid and benzyl methacrylate and 2-hydroxyethyl acrylate, acopolymer of 4-hydroxystyrene and ethyl methacrylate and 2-hydroxyethylacrylate, a copolymer of 4-hydroxystyrene and ethyl methacrylate, acopolymer of 4-hydroxystyrene and styrene, a copolymer of1-n-propoxyethyl methacrylate and benzyl methacrylate, a copolymer of1-n-propoxyethyl acrylate and benzyl methacrylate and 2-hydroxyethylacrylate, a copolymer of maleic anhydride and ethyl methacrylate, acopolymer of 4-hydroxystyrene and maleic anhydride and isopropylacrylate, and the like.

The polymer compound having a phenolic hydroxyl group, includes a phenolnovolak, cresol novolak, naphthol novolak and the like in addition tothe above mentioned ones.

The underlayer coating forming composition of the present inventioncomprises the polymer compound having an epoxy group and the polymercompound having a phenolic hydroxyl group, a carboxyl group, a protectedcarboxyl group or an acid anhydride structure in a content proportion:the polymer compound having an epoxy group/the polymer compound having aphenolic hydroxyl group, a carboxyl group, a protected carboxyl group oran acid anhydride structure that is shown in mass ratio of for example10/1 to 1/10, preferably 5/1 to 1/5, or 3/1 to 1/3. In addition, themolecular weight of the polymer compounds contained in the underlayercoating forming composition according to the present invention is in theterm of weight average molecular weight, 1000 to 500000, preferably 1000to 200000, or 3000 to 150000, or 3000 to 50000.

The underlayer coating forming composition of the present inventioncomprises the polymer compound having an epoxy group and a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure.

Such a polymer compound can be produced by polymerization of an additionpolymerizable monomer having a phenolic hydroxyl group, a carboxylgroup, a protected carboxyl group or an acid anhydride structure with anaddition polymerizable monomer having an epoxy group. As the additionpolymerizable monomers, the above-mentioned monomers can be mentioned,respectively.

Specific examples of the polymer compound having an epoxy group and aphenolic hydroxyl group, a carboxyl group, a protected carboxyl group oran acid anhydride structure used in the underlayer coating formingcomposition of the present invention include for example a copolymer ofacrylic acid and glycidyl acrylate, a copolymer of methacrylic acid andglycidyl methacrylate, a copolymer of methacrylic acid and glycidylmethacrylate and benzyl methacrylate, a copolymer of 4-hydroxystyreneand glycidyl methacrylate, a copolymer of 4-hydroxystyrene andmethacrylic acid and glycidyl methacrylate, a copolymer of styrene andmaleic anhydride and glycidyl methacrylate, a copolymer of glycidylmethacrylate and 1-n-propoxyethyl methacrylate, a copolymer of glycidylmethacrylate and benzyl methacrylate and 1-n-propoxyethyl methacrylate,and the like.

The molecular weight of the polymer compounds contained in theunderlayer coating forming composition according to the presentinvention is in the term of weight average molecular weight, 1000 to500000, preferably 1000 to 200000, or 3000 to 150000, or 3000 to 50000.

The polymer compounds used in the present invention produced from theaddition polymerizable monomers may be any of random polymers, blockpolymers or graft polymers. The polymer compounds can be produced by anymethods such as radical polymerization, anionic polymerization, cationicpolymerization or the like. As the type of polymerization, variousmethods such as solution polymerization, suspension polymerization,emulsion polymerization or bulk polymerization, etc. can be mentioned.

The underlayer coating forming composition according to the presentinvention contains a polymer compound having an epoxy group and acompound with a molecular weight of 2000 or less having at least twophenolic hydroxyl groups, carboxyl groups, protected carboxyl groups oracid anhydride structures.

As the polymer compound having an epoxy group, the above-mentionedpolymer compounds can be used.

The compound with a molecular weight of 2000 or less having at least twophenolic hydroxyl groups includes for example a hydroxystyrene oligomer,a substituted bi-phenol compound, a substituted tris-phenol compound, amethylolated phenol compound, a methylolated bisphenol compound, asubstituted phenol novolak and a substituted cresol novolak.

The compound with a molecular weight of 2000 or less having at least twocarboxyl groups includes for example isophthalic acid, terephthalicacid, 1,2,4-trimellitic acid, pyromellitic acid, adipic acid, maleicacid, itaconic acid, fumaric acid, butane tetracarboxylic acid and thelike. In addition, the compound of formula (1)

may be mentioned. In the formula, p and q is a number of 1 to 6, R₁ ishydrogen atom, C₁₋₆ alkyl group, C₃₋₆ alkenyl group, benzyl group,phenyl group or —(CH₂)_(r)COOH wherein r is a number of 1 to 6. R₁ isfor example methyl group, ethyl group, isopropyl group, n-butyl group,and 2-propenyl group, etc. Specific examples of the compounds of formula(1) are for example tris(2-carboxyethyl) isocyanuric acid,tris(3-carboxypropyl) isocyanuric acid and the like.

The compound with a molecular weight of 2000 or less having at least twoacid anhydride structures includes for example phthalic anhydride,tetrahydrophthalic anhydride, hexahydrophthalic anhydride,methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride,methyl nadic anhydride, dodecylsuccinic anhydride, chlorendic anhydride,pyromellitic anhydride, benzophenone tetracarboxylic anhydride, ethyleneglycol bis(anhydrotrimellitate), methylcyclohexene tetracarboxylicanhydride, trimellitic anhydride, polyazelaic polyanhydride and thelike.

The compound with a molecular weight of 2000 or less having at least twoprotected carboxyl groups includes for example terephthalic acid,trimellitic acid, pyromellitic acid, isophthalic acid,tris(2-carboxyethyl) isocyanuric acid, tris(3-carboxypropyl) isocyanuricacid, adipic acid, maleic acid, itaconic acid, fumaric acid, butanetetracarboxylic acid and the like which are converted with propyl vinylether into a form of hemiacetal.

These compounds can be used alone or in a combination of two or morecompounds.

The underlayer coating forming composition of the present inventioncomprises the polymer compound having an epoxy group and the compoundwith a molecular weight of 2000 or less having at least two phenolichydroxyl groups, carboxyl groups, protected carboxyl groups or acidanhydride structures in a content proportion: the polymer compoundhaving an epoxy group/the compound with a molecular weight of 2000 orless having at least two phenolic hydroxyl groups, carboxyl groups,protected carboxyl groups or acid anhydride structures that is shown inmass ratio of for example 10/1 to 1/10, preferably 5/1 to 1/5, or 3/1 to1/3.

In addition, the underlayer coating forming composition of the presentinvention comprises the compound with a molecular weight of 2000 or lesshaving at least two epoxy groups and the polymer compound having aphenolic hydroxyl group, a carboxyl group, a protected carboxyl group oran acid anhydride structure.

As the polymer compound having a phenolic hydroxyl group, a carboxylgroup, a protected carboxyl group or an acid anhydride structure, theabove-mentioned polymer compounds can be used.

The compound with a molecular weight of 2000 or less having at least twoepoxy groups includes for example triglycidyl-p-aminophenol,tetraglycidyl meta-xylene diamine, tetraglycidyl diaminodiphenylmethane, tetraglycidyl-1,3-bisaminomethylcyclohexane,bisphenol-A-diglycidyl ether, bisphenol-S-diglycidyl ether, resorcinoldiglycidyl ether, diglycidyl phthalate, neopentyl glycol diglycidylether, polypropylene glycol diglycidyl ether, cresol novolakpolyglycidyl ether, tetrabromo bisphenol-A-diglycidyl ether, bisphenolhexafluoro acetone diglycidyl ether, glycerin triglycidyl ether,pentaerythritol diglycidyl ether and the like. In addition, the compoundof formula (2)

may be mentioned. In this formula, wherein A₁, A₂ and A₃ each arehydrogen atom, methyl group or ethyl group, R₂ is hydrogen atom, C₁₋₆alkyl group, C₃₋₆ alkenyl group, benzyl group, phenyl group or a groupof formula (3). R₂ is for example methyl group, ethyl group, isopropylgroup, n-butyl group, 2,3-epoxypropyl group and 2-propenyl group, etc.

Specific examples of the compound formula (2) include for exampletris(2,3-epoxypropyl) isocyanurate, monoallyl diglycidyl isocyanurateand the like. These compounds can be used alone or in a combination oftwo or more compounds.

The underlayer coating forming composition of the present inventioncomprises the compound with a molecular weight of 2000 or less having atleast two epoxy groups and the polymer compound having a phenolichydroxyl group, a carboxyl group, a protected carboxyl group or an acidanhydride structure in a content proportion: the compound with amolecular weight of 2000 or less having at least two epoxy groups/thepolymer compound having a phenolic hydroxyl group, a carboxyl group, aprotected carboxyl group or an acid anhydride structure that is shown inmass ratio of for example 10/1 to 1/10, preferably 5/1 to 1/5, or 3/1 to1/3.

As mentioned above, the underlayer coating forming composition of thepresent invention comprises a component having an epoxy group (a polymercompound, a compound) and a component having a phenolic hydroxy group, acarboxyl group, a protected carboxyl group or an acid anhydridestructure (a polymer compound, a compound). When this composition isapplied on a semiconductor substrate and baked to form an underlayercoating, the epoxy group is reacted with the phenolic hydroxy group,carboxyl group, protected carboxyl group or acid anhydride structure,and thereby the ring-opening reaction of the epoxy group occurs. Inaddition, the protected carboxyl group provides a carboxyl group duringthe baking, and then the reaction thereof with an epoxy group occurs.That is, the polymer compounds are reacted each other or the polymercompound is reacted with the compound with a molecular weight of 2000 orless, and the result of it, three-dimensional crosslinked structureformed between the polymer compounds or from the polymer compound andthe compound with a molecular weight of 2000 or less. And, due to thecrosslinked structure, the formed underlayer coating becomes tight, andcomes to have a low solubility in an organic solvent generally used forthe photoresist composition applied on the underlayer coating, such asethylene glycol monomethyl ether, ethyl cellosolve acetate, diethyleneglycol monoethyl ether, propylene glycol, propylene glycol monomethylether, propylene glycol monomethyl ether acetate, propylene glycolpropyl ether acetate, toluene, methyl ethyl ketone, cyclohexanone, ethyl2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethylethoxyacetate, methylpyruvate, ethyl lactate, butyl lactate, etc. Thus,the underlayer coating formed from the underlayer coating formingcomposition according to the present invention causes no intermixingwith photoresists.

In addition, as the reaction of an epoxy group with a phenolic hydroxygroup, a carboxyl group, a protected carboxyl group or an acid anhydridestructure proceeds easily under a baking condition, the reaction doesnot require any catalyst. Therefore, for the underlayer coatingcomposition of the present invention, it is not required to add anysulfonic acid compound that has been generally used as a crosslinkingcatalyst in the composition for forming the prior crosslinkableunderlayer coating.

The compound with a molecular weight of 2000 or less is required tocontain at least two epoxy groups, phenolic hydroxy groups, carboxylgroups, protected carboxyl groups or acid anhydride structures forforming crosslinkage structure. The compounds having three or more epoxygroups, phenolic hydroxy groups, carboxyl groups, protected carboxylgroups or acid anhydride structures are preferably used.

The underlayer coating forming composition according to the presentinvention may contain further light absorbing compounds, rheologycontrolling agents, adhesion auxiliaries, surfactants, etc. in additionto the above described ones, if necessary.

The light absorbing compound that can be used are any compounds having ahigh absorption for light at photosensitive characteristic wavelengthregion of photosensitive components in a photoresist layer provided onthe underlayer coating, and prevents standing wave caused by reflectionfrom a substrate or random reflection due to unevenness on the substratesurface, it can be used without any limitation. When the light absorbingcompound is added to the underlayer coating forming composition, theresulting underlayer coating has a high effect of preventing reflectedlight and excellent function as an anti-reflective coating.

As the light absorbing compounds, can be used benzophenone compounds,benzotriazole compounds, azo compounds, naphthalene compounds,anthracene compounds, anthraquinone compounds, triazine compounds,triazine trione compounds, quinoline compounds and the like. Naphthalenecompounds, anthracene compounds, triazine compounds and triazine trionecompounds are preferably used. In addition, it is preferable that thelight absorbing compound can be reacted with the above-mentionedcomponent having an epoxy group, and therefore compounds having acarboxyl group or a phenolic hydroxyl group are preferably used.Specific examples include for example 1-naphthalene carboxylic acid,2-naphthalene carboxylic acid, 1-naphthol, 2-naphthol, naphthyl acetate,1-hydroxy-2-naphthalene carboxylic acid, 3-hydroxy-2-naphthalenecarboxylic acid, 3,7-dihydroxy-2-naphthalene carboxylic acid,6-bromo-2-hydroxynaphthalene, 2,6-naphthalene dicarboxylic acid,9-anthracene carboxylic acid, 10-bromo-9-anthracene carboxylic acid,anthracene-9,10-carboxylic acid, 1-anthracene carboxylic acid,1-hydroxyanthracene, 1,2,3-anthracenetriol, 2,7,9-anthracenetriol,benzoic acid, 4-hydroxybenzoic acid, 4-bromobenzoic acid, 3-iodobenzoicacid, 2,4,6-tribromophenol, 2,4,6-tribromoresorcinol,3,4,5-triiodobenzoic acid, 2,4,6-triiodo-3-aminobenzoic acid,2,4,6-triiodo-3-hydroxybenzoic acid, 2,4,6-tribromo-3-hydroxybenzoicacid and the like.

These light absorbing compounds can be used alone or in a combination oftwo or more compounds. When the light absorbing compounds are containedin the underlayer coating forming composition of the present invention,the blending amount is 30 mass % or less, for example 1 to 20 mass % or1 to 10 mass % in the solid content.

The rheology controlling agents are added mainly aiming at increasingthe flowability of the underlayer coating forming composition and inparticular in the baking step, increasing fill property of theunderlayer coating forming composition into the inside of holes.Specific examples thereof include phthalic acid derivatives such asdimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dihexylphthalate or butyl isodecyl phthalate; adipic acid derivatives such asdi-n-butyl adipate, diisobutyl adipate, diisooctyl adipate or octyidecyladipate; maleic acid derivatives such as di-n-butyl maleate, diethylmaleate or dinonyl maleate; oleic acid derivatives such as methyloleate, butyl oleate or tetrahydrofurfuryl oleate; or stearic acidderivatives such as n-butyl stearate or glyceryl stearate. The rheologycontrolling agents are added in proportions of usually less than 10 mass% in the solid content of the underlayer coating forming composition.

The adhesion auxiliaries are added mainly for the purpose of increasingthe adhesion between a substrate, or an anti-reflective coating or aphotoresist and an underlayer coating formed from an underlayer coatingforming composition, in particular preventing the detachment indevelopment. Specific examples thereof include chlorosilanes such astrimethylchlorosilane, dimethylvinylchlorosilane, methyldiphenylchlorosilane or chloromethyldimethyl chlorosilane; alkoxysilanessuch as dimethyldiethoxysilane, methyldimethoxysilane,dimethylvinylethoxysilane, γ-methacryloxypropyltrimethoxysilane,diphenyldimethoxysilane or phenyltriethoxysilane; silazanes such ashexamethyldisilazane, N,N′-bis(trimethylsilyl)urea,dimethyltrimethylsilylamine or trimethylsilylimidazole; silanes such asvinyltrichlorosilane, γ-chloropropyltrimethoxysilane,γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane orγ-methacryloxypropyltrimethoxysilane; heterocyclic compounds such asbenzotriazole, benzimidazole, indazole, imidazole,2-mercaptobenzimidazole, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole,urazole, thiouracyl, mercaptoimidazole or mercaptopyrimidine; ureas suchas 1,1-dimethylurea or 1,3-dimethylurea. The adhesion auxiliaries areadded in proportions of usually less than 2 mass %, in the solid contentof the underlayer coating forming composition.

The underlayer coating forming composition according to the presentinvention may contain surfactants with view to preventing the occurrenceof pinholes or striations and further increasing coatability not tocause surface unevenness. As the surfactants, mention may be made of,for example, nonionic surfactants such as polyoxyethylene alkyl ethers,e.g., polyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene cetyl ether, polyoxyethylene oleyl ether, etc.,polyoxyethylene alkyl allyl ethers, e.g., polyoxyethylene octyl phenolether, polyoxyethylene nonyl phenol ether, etc.;polyoxyethylene/polyoxypropylene block copolymers, sorbitan fatty acidesters, e.g., sorbitan monolaurate, sorbitan monopalmitate, sorbitanmonostearate, sorbitan monooleate, sorbitan trioleate, sorbitantristearate, etc., polyoxyethylene sorbitan fatty acid esters, e.g.,polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitanmonopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylenesorbitan trioleate, polyoxyethylene sorbitan tristearate, etc.; fluorinebased surfactants, e.g., trade name: EFTOP EF301, EF303, EF352(manufactured by Tochem Products Co., Ltd.), trade name: MEGAFAC F171,F173, R-08, R-30 (manufactured by Dainippon Ink and Chemicals, Inc.),trade name: FLUORAD FC430, FC431 (manufactured by Sumitomo 3M Limited),trade name: ASAHI GUARD AG710, SURFLON S-382, SC101, SC102, SC103,SC104, SC105, SC106 (manufactured by Asahi Glass Co., Ltd.);organosiloxane polymer KP341 (manufactured by Shinetsu Chemical Co.,Ltd.), etc. The blending amount of the surfactants is usually 1 mass %or less in the solid content of the underlayer coating formingcomposition according to the present invention. The surfactants may beadded singly or two or more of them may be added in combination.

In the underlayer coating forming composition of the present invention,several solvents for dissolving the solid contents such as theabove-mentioned polymer compounds and the like can be used. As thesolvents, use may be made of ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolveacetate, diethylene glycol monomethyl ether, diethylene glycol monoethylether, propylene glycol, propylene glycol monomethyl ether, propyleneglycol monomethyl ether acetate, propylene glycol propyl ether acetate,toluene, xylene, methyl ethyl ketone, cyclopentanone, cyclohexanone,ethyl 2-hydroxypropionate, ethyl 2-hydroxy-2-methylpropionate, ethylethoxyacetate, ethyl hydroxyacetate, methyl 2-hydroxy-3-methylbutanoate,methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethyl3-ethoxypropionate, methyl 3-ethoxypropionate, methylpyruvate, ethylpyruvate, ethyl acetate, butyl acetate, ethyl lactate, butyl lactate,etc. These solvents may be used singly or in combination of two or moreof them. Further, high boiling solvents such as propylene glycolmonobutyl ether or propylene glycol monobutyl ether acetate, etc. may bemixed.

Hereinafter, the utilization of the underlayer coating formingcomposition of the present invention is described.

On a semiconductor substrate (for example, silicon/silicon dioxide coatsubstrate, silicon nitride substrate, glass substrate, ITO substrate orthe like), the underlayer coating forming composition of the presentinvention is coated by a suitable coating method, for example, with aspinner, a coater or the like, and thereafter the substrate is baked tofabricate an underlayer coating. The conditions of baking are suitablyselected from baking temperature of 80 to 250° C. and baking time of 0.3to 60 minutes. The thickness of the underlayer coating is for example0.01 to 3.0 μm, or for example 0.03 to 1.0 μm.

Next, a photoresist is formed directly on the underlayer coating orafter forming an anti-reflective coating, and then a substrateprocessing is carried out by exposure to light, development and dryetching.

The underlayer coating formed from the underlayer coating formingcomposition according to the present invention is completely removedfinally after exposure to light and development of photoresist, andsubstrate processing, and the like in a process of manufacture ofsemiconductor device. The removal is generally carried out by dryetching.

As photoresist to be coated and formed as an upper layer of theunderlayer coating of the present invention, any of negative type andpositive type photoresists may be used. The photoresist includes apositive type photoresist consisting of a novolak resin and1,2-naphthoquinone diazide sulfonic acid ester, a chemically-amplifiedtype photoresist which consists of a photoacid generator and a binderhaving a group which is decomposed with an acid and increases alkalidissolution rate, a chemically-amplified type photoresist consisting ofan alkali-soluble binder, a photoacid generator, and a low molecularcompound which is decomposed with an acid and increases the alkalidissolution rate of the photoresist, a chemically-amplified photoresistconsisting of a photoacid generator, a binder having a group which isdecomposed with an acid and increases the alkali dissolution rate, and alow molecular compound which is decomposed with an acid and increasesthe alkali dissolution rate of the photoresist. For example, trade name:APEX-E manufactured by Shipley Company, trade name: PAR710 manufacturedby Sumitomo Chemical Co., Ltd., and trade name: SEPR430 manufactured byShinetsu Chemical Co., Ltd., and the like can be mentioned. And, aphotoresist is formed, thereafter it can be exposed to light through apredetermined mask, developed, rinsed and dried to obtain a photoresistpattern. If necessary, post exposure bake (PEB) may be performed.

As developers for positive type photoresists having the underlayercoating formed by use of the underlayer coating forming composition forlithography according to the present invention, the following aqueoussolutions of alkalis can be used: inorganic alkali such as sodiumhydroxide, potassium hydroxide, sodium carbonate, sodium silicate,sodium metasilicate or ammonia water, etc., primary amines such asethylamine or n-propylamine, etc., secondary amines such as diethylamineor di-n-butylamine, etc., tertiary amines such as triethylamine ormethyldiethylamine, etc., alcohol amines such as dimethylethanol amineor triethanol amine, etc., quaternary ammonium salt such astetramethylammonium hydroxide, tetraethylammonium hydroxide or choline,etc., cyclic amine such as pyrrole or piperidine, etc. Furthermore, asuitable amount of alcohols such as isopropyl alcohol or surfactantssuch as anionic surfactant can be added to the above-mentioned aqueoussolution of alkalis. Among them, preferable developers are quaternaryammonium salts, and more preferably tetramethylammonium hydroxide andcholine.

Before or after forming the underlayer coating layer of the presentinvention on a semiconductor substrate, an organic anti-reflectivecoating layer may be applied and formed. The anti-reflective coatingcomposition used in such a case is not specifically limited, and can bearbitrarily selected from those conventionally used in the priorlithography process, and used. In addition, the anti-reflective coatingcan be formed by coating by the conventional method, for example, with aspinner or a coater, and baking. The anti-reflective coating compositionincludes for example one containing as main components a light absorbingcompound, a resin and a solvent, one containing as main components aresin having a light absorbing group through chemical bond, acrosslinking agent and a solvent, one containing as main components alight absorbing compound, a crosslinking agent and a solvent, onecontaining as main components a polymer type crosslinking agent having alight absorbing property and a solvent, and the like. Theanti-reflective coating composition may contain an acid component, anacid generator component, a rheology controlling agent, or the like, ifnecessary. The light absorbing compounds that can be used are anycompounds having a high absorption for light at photosensitivecharacteristic wavelength region of the photosensitive component in thephotoresist provided on the anti-reflective coating, and include forexample benzophenone compounds, benzotriazole compounds, azo compounds,naphthalene compounds, anthracene compounds, anthraquinone compounds,triazine compounds, and the like. The resins include polyesters,polyimides, polystyrenes, novolak resins, polyacetal resins, acrylicresins, and the like. The resins having a light absorbing group throughchemical bond include resins having a light absorbing aromatic ringstructure such as anthracene ring, naphthalene ring, benzene ring,quinoline ring, quinoxaline ring or thiazole ring.

The substrates on which the underlayer coating forming composition ofthe present invention is applied may be substrates on which an inorganicanti-reflective coating is formed by CVD method or the like, and theunderlayer coating forming composition of the present invention can becoated thereon.

The underlayer coating formed from the underlayer coating formingcomposition of the present invention may contain an absorption for lightused in the lithography process. In such a case, the underlayer coatingcan be used as a layer having a prevent effect against light reflectedfrom the substrate, that is, as an anti-reflective coating.

In case where the underlayer coating is used as an anti-reflectivecoating in the lithography process by use of irradiation light of KrFexcimer laser beam (wavelength 248 nm), it is preferable that the solidcontent in the underlayer coating forming composition contains acomponent containing an anthracene ring or a naphthalene ring. In casewhere the underlayer coating is used as an anti-reflective coating inthe lithography process by use of irradiation light of ArF excimer laserbeam (wavelength 193 nm), it is preferable that the solid content in theunderlayer coating forming composition contains a component containing abenzene ring. In case where the underlayer coating is used as ananti-reflective coating in the lithography process by use of irradiationlight of F2 excimer laser beam (wavelength 157 nm), it is preferablethat the solid content in the underlayer coating forming compositioncontains a component containing a bromine atom or an iodine atom.

Further, the underlayer coating of the present invention can be used asa layer for preventing an interaction between the substrate and thephotoresist, as a layer having a function that prevents an adverseeffect against the substrate by the material used for the photoresist orby substances formed on exposure to light of the photoresist, as a layerhaving a function that prevents diffusion and adverse effects ofsubstances formed in the substrate on baking under heating to the upperlayer photoresist, or as a barrier layer for reducing any poisoningeffect of the photoresist layer by the semiconductor substratedielectric layer.

In addition, the underlayer coating formed from the underlayer coatingforming composition can be used as a filling agent that can fill viaholes without gap or as a flattening agent for flattening a substratesurface, by applying it for the substrate on which via holes are formedand which is used in dual damascene process.

Hereinafter, the present invention will be described based on examplesbut the present invention is not limited thereto.

EXAMPLES Synthetic Example 1

In 64 g of ethyl lactate, 5.44 g of benzyl methacrylate, 5.0 g ofglycidyl methacrylate and 5.6 g of 2-hydroxyethyl methacrylate weredissolved, then the temperature of the reaction solution was raised to70° C. and at the same time nitrogen was flowed to the reactionsolution. Thereafter 0.2 g of azobisisobutyronitrile as a polymerizationinitiator was added. After stirring under nitrogen atmosphere for 24hours, 0.05 g of 4-methoxyphenol as a short-stop was added to obtain asolution containing a copolymer of benzyl methacrylate, glycidylmethacrylate and 2-hydroxyethyl methacrylate. GPC analysis of theresulting polymer compound showed that it had a weight average molecularweight of 25000 in terms of standard polystyrene.

Synthetic Example 2

In 64 g of ethyl lactate, 5.44 g of benzyl methacrylate and 10.6 g ofglycidyl methacrylate were dissolved, then the temperature of thereaction solution was raised to 70° C. and at the same time nitrogen wasflowed to the reaction solution. Thereafter 0.2 g ofazobisisobutyronitrile as a polymerization initiator was added. Afterstirring under nitrogen atmosphere for 24 hours, 0.05 g of4-methoxyphenol as a short-stop was added to obtain a solutioncontaining a copolymer of benzyl methacrylate and glycidyl methacrylate.GPC analysis of the resulting polymer compound showed that it had aweight average molecular weight of 22000 in terms of standardpolystyrene.

Synthetic Example 3

In 64 g of ethyl lactate, 5.44 g of benzyl methacrylate, 5.3 g ofmethacrylic acid and 5.3 g of glycidyl methacrylate were dissolved, thenthe temperature of the reaction solution was raised to 70° C. and at thesame time nitrogen was flowed to the reaction solution. Thereafter 0.2 gof azobisisobutyronitrile as a polymerization initiator was added. Afterstirring under nitrogen atmosphere for 24 hours, 0.05 g of4-methoxyphenol as a short-stop was added to obtain a solutioncontaining a copolymer of benzyl methacrylate, methacrylic acid andglycidyl methacrylate. GPC analysis of the resulting polymer compoundshowed that it had a weight average molecular weight of 114000 in termsof standard polystyrene.

Synthetic Example 4

In 64 g of ethyl lactate, 16 g of glycidyl methacrylate was dissolved,then the temperature of the reaction solution was raised to 70° C. andat the same time nitrogen was flowed to the reaction solution.Thereafter 0.2 g of azobisisobutyronitrile as a polymerization initiatorwas added. After stirring under nitrogen atmosphere for 24 hours, 0.05 gof 4-methoxyphenol as a short-stop was added to obtain a solutioncontaining polyglycidyl methacrylate. GPC analysis of the resultingpolymer compound showed that it had a weight average molecular weight of20000 in terms of standard polystyrene.

Synthetic Example 5

In 80 g of propylene glycol monomethyl ether, 10 g of cresol novolakresin (manufactured by Asahi Chiba Co., Ltd., trade name: ECN1299,weight average molecular weight: 3900) was dissolved. To the resultingsolution, 9.7 g of 9-anthracene carboxylic acid and 0.26 g of benzyltriethyl ammonium chloride were added, then the reaction was carried outat 105° C. for 24 hours to obtain a solution containing the polymercompound of formula (4). GPC analysis of the resulting polymer compoundshowed that it had a weight average molecular weight of 5600 in terms ofstandard polystyrene.

Example 1

0.3 g of tris(2-carboxyethyl)isocyanurate was mixed with 6 g of asolution containing 1.2 g of the polymer compound obtained in SynthesisExample 1, 28.5 g of ethyl lactate was added thereto. Thereafter, theresulting solution was filtered through a micro filter made ofpolyethylene having a pore diameter of 0.10 μm, and then filteredthrough a micro filter made of polyethylene having a pore diameter of0.05 μm to prepare an underlayer coating forming composition solution.

Example 2

0.3 g of tris(2-carboxyethyl)isocyanurate was mixed with 6 g of asolution containing 1.2 g of the polymer compound obtained in SynthesisExample 2, 28.5 g of ethyl lactate was added thereto. Thereafter, theresulting solution was filtered similarly to the procedure in Example 1to prepare an underlayer coating forming composition solution.

Example 3

0.8 g of poly(acrylic acid) was mixed with 0.7 g oftris(2,3-epoxypropyl)isocyanurate, 28.5 g of ethyl lactate was addedthereto. Thereafter, the resulting solution was filtered similarly tothe procedure in Example 1 to prepare an underlayer coating formingcomposition solution.

Example 4

To 7.5 g of a solution containing 1.5 g of the polymer compound obtainedin Synthesis Example 3, 22.5 g of ethyl lactate was added. Thereafter,the resulting solution was filtered similarly to the procedure inExample 1 to prepare an underlayer coating forming composition solution.

Example 5

3.75 g of a solution containing 0.75 g of the polymer compound obtainedin Synthesis Example 4 was mixed with 0.75 g of poly(acrylic acid), 25.5g of ethyl lactate was added thereto. Thereafter, the resulting solutionwas filtered similarly to the procedure in Example 1 to prepare anunderlayer coating forming composition solution.

Comparative Example 1

To 10 g of a solution containing 2 g of the polymer compound obtained inSynthesis Example 5, 0.53 g of hexamethoxy methyl melamine as acrosslinking agent and 0.05 g of p-toluene sulfonic acid monohydratewere mixed, and the resulting solution was dissolved in 14.3 g of ethyllactate, 1.13 g of propylene glycol monomethyl ether and 2.61 g ofcyclohexanone to obtain 9% solution. Thereafter, the resulting solutionwas filtered similarly to the procedure in Example 1 to prepare anunderlayer coating forming composition solution.

Dissolution Test in Organic Solvent

The solutions obtained in Examples 1 to 5 and Comparative Example 1 werecoated on silicon wafers by means of a spinner. The coated siliconwafers were baked at 205° C. for 1 minute on a hot plate to formunderlayer coatings for lithography (film thickness 0.23 μm). Theunderlayer coatings were dipped in a solvent used for photoresists, forexample ethyl lactate and propylene glycol monomethyl ether and as aresult it was confirmed that the resulting underlayer coatings wereinsoluble in these solvents.

Test of Intermixing

The solutions obtained in Examples 1 to 5 and Comparative Example 1 werecoated on silicon wafers by means of a spinner. The coated siliconwafers were baked at 205° C. for 1 minute on a hot plate to formunderlayer coatings, and the film thickness thereof was measured (filmthickness 0.23 μm). On each underlayer coating was coated a commerciallyavailable photoresist solution (manufactured by Sumitomo Chemical Co.,Ltd.; trade name: PAR710, etc.) by means of a spinner. The coated waferswere heated at 90° C. for 1 minute on a hot plate. After exposure of thephotoresists to light, post exposure bake (PEB) was performed at 90° C.for 1.5 minute. After developing the photoresists, the film thickness ofthe underlayer coatings was measured and it was confirmed that nointermixing occurred between the underlayer coatings obtained fromsolutions prepared in Examples 1 to 5 and Comparative Example 1 and thephotoresist layers.

Measurement of Optical Parameter

The underlayer coating forming composition solution prepared in Example1 was coated on a silicon wafer by means of a spinner. The coatedsilicon wafer was baked at 205° C. for 1 minute on a hot plate to forman underlayer coating (film thickness 0.08 μm). On the underlayercoating, refractive index (n) and attenuation coefficient (k) at awavelength of 193 nm were measured with a spectroscopic ellipsometer. Asa result of it, refractive index (n) was 1.82 and attenuationcoefficient (k) was 0.32.

Measurement of Dry Etching Rate

The underlayer coating forming composition solution prepared in Example1 was coated on a silicon wafer by means of a spinner. The coatedsilicon wafer was baked at 205° C. for 1 minute on a hot plate to forman underlayer coating. Then, dry etching rate on underlayer coating wasmeasured with RIE system ES401 manufactured by Nippon Scientific Co.,Ltd. under the condition in which CF₄ was used as dry etching gas.Similarly, a photoresist solution (manufactured by Sumitomo ChemicalCo., Ltd., trade name: PAR710) was coated on a silicon wafer by means ofa spinner, and heated to form a photoresist coating. Then, dry etchingrate on the photoresist was measured with RIE system ES401 manufacturedby Nippon Scientific Co., Ltd. under the condition in which CF₄ was usedas dry etching gas. Comparison of the dry etching rate between theunderlayer coating in Example 1 and the photoresist (trade name: PAR710)manufactured by Sumitomo Chemical Co., Ltd. showed that the dry etchingrate of the underlayer coating was 1.3 time that of the photoresist.

As mentioned above, present invention relates to an underlayer coatingformed by use of crosslinking reaction that dose not require a strongacid catalyst, and an underlayer coating forming composition for formingthe underlayer coating.

The underlayer coating forming composition of the present inventioncontains no strong acid catalyst, and therefore it is excellent in shelfstability.

The underlayer coating forming composition of the present invention canprovide an excellent underlayer coating that has a high dry etching ratecompared with photoresists, and cause no intermixing with photoresists.In addition, the underlayer coating of the present invention can be usedas an anti-reflective coating, a flattening coating, or a coating forpreventing contamination of a photoresist layer. Consequently, thepresent invention enables the formation of photoresist pattern inlithography process of the production of semiconductor device to becarried out easily and in a high accuracy.

1. A resist underlayer anti-reflective coating forming composition foruse in a lithography process of manufacture of a semiconductor devicecomprising: a polymer compound produced by addition polymerizationhaving an epoxy group; a compound with a molecular weight of 2000 orless having at least two carboxyl groups, or protected carboxyl groups;a solvent; and a light absorbing compound, wherein the resist underlayeranti-reflective coating forming composition contains no strong acidcatalyst.
 2. A resist underlayer anti-reflective coating formingcomposition for use in a lithography process of manufacture of asemiconductor device comprising: an s-triazine trione skeleton compoundwith a molecular weight of 2000 or less having at least two epoxygroups; a polymer compound having a phenolic hydroxyl group, a carboxylgroup, a protected carboxyl group or an acid anhydride structure; and asolvent, wherein the resist underlayer anti-reflective coating formingcomposition contains no strong acid catalyst.
 3. The underlayer coatingforming composition according to claim 2, wherein the polymer compoundhaving a carboxyl group is a compound having acrylic acid or methacrylicacid as a unit structure.
 4. The underlayer coating forming compositionaccording to claim 2, wherein the polymer compound having a phenolichydroxyl group is a compound having hydroxystyrene as a unit structure.5. The underlayer coating forming composition according to claim 2,wherein the compound with a molecular weight of 2000 or less having atleast two epoxy groups is a compound having at least three epoxy groupsand no aromatic ring structure.
 6. The underlayer coating formingcomposition according to claim 2, wherein the compound with a molecularweight of 2000 or less having at least two epoxy groups is a compound offormula (2)

wherein A₁, A₂ and A₃ each are hydrogen atom, methyl group or ethylgroup, R₂ is hydrogen atom, C₁₋₆ alkyl group, C₃₋₆ alkenyl group, benzylgroup, phenyl group or a group of formula (3)


7. A method for forming photoresist patterns for use in manufacture ofsemiconductor devices, comprising coating an underlayer formingcomposition on a semiconductor substrate, and baking it to form anunderlayer coating, forming a photoresist layer on the underlayercoating, exposing the semiconductor substrate covered with theunderlayer coating and the photoresist layer to light, and developingthe photoresist layer after the exposure to light, wherein theunderlayer forming composition comprises: a polymer compound produced byaddition polymerization having an epoxy group; a compound with amolecular weight of 2000 or less having at least two carboxyl groups, orprotected carboxyl groups; and a solvent, wherein the resist underlayeranti-reflective coating forming composition contains no strong acidcatalyst.
 8. The method for forming photoresist pattern according toclaim 7, wherein the exposure to light is carried out with a light of awavelength of 248 nm, 193 nm or 157 nm.